In marketing of hydrocarbon fluids, such as kerosene, cleaning fluid, gasoline additives, and other bulk products, distribution from a refinery to a sales point is normally through a bulk plant or distribution terminal. Such a terminal serves as a supply center for consumer sales outlets, for example, service stations, cleaning plants, manufacturing facilities and the like. This type of bulk liquid distribution center frequently differs from fuel terminals for automotive and aviation sales where volume of sales may justify the cost of laying a pipe line from a refinery to the bulk storage or distribution plant. Fuel products from local bulk storage at an airport, gasoline or diesel distributor, may however, in turn, be distributed in discrete quantities or "batches" to planes, or automotive fuel stations by a local unloading header arrangement. Customarily, in sale and distribution of bulk products, other than motor fuels, such products are delivered in batches of a few hundred gallons to a bulk station or to a sub-distributor through a tank truck. In batch handling of kerosene, cleaning fluid and the like, delivery from compartments on a tank truck are by a gravity hose connectable to a storage tank through a pipe delivery system. The delivery system normally includes a hose coupler for interconnecting a truck delivery hose to an unloading chamber, a pipe delivery line and pump for pumping liquid to the storage tank. The hose coupler is generally located at grade, or below, for gravity flow of hydrocarbons from a tank truck compartment through an unloading valve located a few feet above ground level. Liquid flows by gravity into the unloading pot or chamber. The purpose of the unloading chamber is to assure that there is an adequate head of liquid above the bulk storage pump inlet, to prevent pump "cavitation" which might introduce air into the liquid.
Pollution of earth, air, or water in the United States and other developed parts of the world is now controlled by local and national laws, or regulations, which require that all potential sources of such pollution be carefully controlled. In general, handling of all hydrocarbon liquids or fluids requires that spills be avoided wherever possible and that any spills be collected. Heretofore this has required manual or machine cleanup of any such spills. In transferring bulk liquid hydrocarbon in batches from a central distribution terminal is by a tank truck or a tank car. As noted above, liquid delivery from the tank truck compartment usually depends upon gravity flow through a flexible loading hose from the tank truck or car to a pipe system connected to a storage tank. Additionally, distribution from a major storage terminal to another point of smaller usage may also require delivery by a tank truck from the intermediate storage tank to an ultimate user, such as a paint manufacturer, cleaning establishment, or a local gasoline distributor. In such systems, liquid delivery from the tank truck to such a local storage system is also by gravity flow through a flexible loading hose. Further, in distribution of product in a storage tank to a tank truck compartment for such delivery, flow may be reversed and pumped through the loading hose up into the truck tank. In systems of this type, a control valve for flow into, or out of, the truck compartment is at the bottom of the tank truck. When the truck valve is closed the hose will normally retain a small amount of liquid after the supply is shut off. The hose must then be drained through the loading interconnect, or hose connection, between the hose and the storage tank piping system. It is customary to avoid spillage directly at the tank truck, because of the hazard and difficulty of collecting any spillage under the tank truck outlet, by disconnecting the hose at the downstream connector. Such connector is generally at ground level or below. Accordingly, leakage often occurs inadvertently, and without possibility of prevention, when the delivery hose is disconnected from such an unloading header connector. Even when great care is exerted to drain the hose during the disconnect step, leakage may occur around the connector onto the ground or in the vicinity of the unloading connector.
It has been known to use an unloading chamber below the hose connector. This unloading chamber usually is larger in diameter than the hose to permit enough liquid to be accumulated in the system to fill the pipe line up to a pump, normally positioned near the inlet line. The off-loaded liquid is then pumped from the chamber to a storage tank through normal piping. One particular purpose of having a larger volume storage tank is to assure that the pump has an adequate volume of liquid above the line prior to starting the pump. Thus, the pump will not entrap and incorporate air into the hydrocarbon liquid as it is being pumped into the tank. However, no system for recovering spillage or leakage upon connecting or disconnecting a tank truck unloading hose has been known prior to the present invention.
In accordance withthe present invention, an open top closure box overlies and forms a cover for the loading pot. The sides of the box extend above the hose connector so that the connector lies entirely within the open top box. Desirably, the top of the open box lies below grade so that both the unloading chamber and the box are below the level of the delivery compartment of the tank truck and the hose connector on the truck. Further, the box and chamber are below grade to prevent spills around them. In this way fluid flows from the tank truck under gravity and any liquid spilled from the connector flows into and is captured within the open box top. Further, in accordance with the arrangement of the present invention, at least the base of the box is tilted toward one end, and a sump pot is arranged in parallel to the unloading chamber and at the low end of the box. A drain line from the sump pot is connected to a slop tank. The drain line also includes a vapor recovery line, which may be connected to a vapor recovery system in parallel with a vapor recovery connection through a gas-only valve at the top of the unloading pot. In a preferred form, a removable grating overlies at least a portion of the open-box and covers the hose connector, as well as both the sump pot and the unloading chamber assembly. In an alternative form, a plurality of unloading chambers, each connected to separate storage lines and storage tanks, are integral with the bottom of the open-box and in parallel with a single sump pot.